To enable directed broadcasts on an individual interface instead of globally for all interfaces, enter the ip directed-broadcast command at
the interface conguration level as shown in the following example.
device # configure terminal
device(config)# interface ethernet 1/1/1
device(config-if-1/1/1 # ip directed-broadcast
Disabling forwarding of IP source-routed packets
A source-routed packet
species the exact router path for the packet. The packet species the path by listing the IP addresses of the
router interfaces through which the packet must pass on its way to the destination. The Layer 3 switch supports both types of IP source
routing:
• Strict source routing - Requires the packet to pass through only the listed routers. If the Layer 3 switch receives a strict source-
routed packet but cannot reach the next hop interface specied by the packet, the Layer 3 switch discards the packet and sends
an ICMP Source-Route-Failure message to the sender.
NOTE
The Layer 3 switch allows you to disable sending of the Source-Route-Failure messages.
• Loose source routing - Requires that the packet pass through all of the listed routers but also allows the packet to travel through
other routers, which are not listed in the packet.
The Layer 3 switch forwards both types of source-routed packets by default. To disable the feature, use either of the following methods.
You cannot enable or disable strict or loose source routing separately.
To disable forwarding of IP source-routed packets, enter the no ip source-route command.
device # configure terminal
device(config)# no ip source-route
Syntax: [no] ip source-route
To re-enable forwarding of source-routed packets, enter the ip source-route command.
device # configure terminal
device(config)# ip source-route
Enabling support for zero-based IP subnet broadcasts
By default, the Layer 3 switch treats IP packets with all ones in the host portion of the address as IP broadcast packets. For example, the
Layer 3 switch treats IP packets with 10.157.22.255/24 as the destination IP address as IP broadcast packets and forwards the
packets to all IP hosts within the 10.157.22.x subnet (except the host that sent the broadcast packet to the Layer 3 switch).
Most IP hosts are
congured to receive IP subnet broadcast packets with all ones in the host portion of the address. However, some
older IP hosts instead expect IP subnet broadcast packets that have all zeros instead of all ones in the host portion of the address. To
accommodate this type of host, you can enable the Layer 3 switch to treat IP packets with all zeros in the host portion of the destination
IP address as broadcast packets.
NOTE
When you enable the Layer 3 switch for zero-based subnet broadcasts, the Layer 3 switch still treats IP packets with all ones
the host portion as IP subnet broadcasts too. Thus, the Layer 3 switch can be congured to support all ones only (the default) or
all ones and all zeroes.
NOTE
This feature applies only to IP subnet broadcasts, not to local network broadcasts. The local network broadcast address is still
expected to be all ones.
Conguring IP parameters - Layer 3 switches
FastIron Ethernet Switch Layer 3 Routing
60 53-1003627-04
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